1. Field of the Invention
The present invention relates to a method of reducing the communication charge that is incurred when executing an application program, esp., a network game program, on a portable terminal.
2. Description of the Related Art
Initially, video games were played individually by users using a game-dedicated terminal or a personal computer (PC) to execute a game program stored in a ROM medium (e.g., a ROM cartridge, a CD-ROM, a DVD-ROM, etc.). Thereafter, in accompaniment with the spread of the Internet, network games were introduced which many users can play at the same time by connecting, via the Internet, terminals capable of executing game programs, such as game-dedicated terminals or PCs. In recent years, environments have even come into being in which users can play network games using a portable terminal such as a portable telephone or a personal digital assistant (PDA) to execute a Java® application program or a BREW® application program.
The user can play the network game as long as the user can connect to the Internet. In other words, sometimes the terminal (game-dedicated terminal, PC, portable terminal, etc.) used by the user when playing a network game differs depending on the circumstance. For instance, sometimes the user begins playing a game on a home PC and then continues the game on a PC disposed in an Internet café or on the user's portable telephone at a destination outside of the home.
The information terminal used by the user also changes when the user changes portable telephone models. In third-generation portable telephones, consideration is being given to allow users to use the same telephone number and billing information, even if the telephone is different, by replacing the user identity module (UIM) card, and it is expected that the frequency with which users change models will increase in the future.
Thus, in order for the user to be able to continue the game that the user had been playing even when the user changes terminals, it is necessary for the save data of the user (data necessary for the progression of the network game in relation to that user; e.g., status of progress, score, list of acquired items, setting information, etc.) to be synchronized for each terminal that the user uses. This is because the save data is not always initially stored in the newly used information terminal. For example, when the user changes portable telephone models, the copyrighted contents (music, game programs, etc.) downloaded to the old portable telephone cannot as a rule be transferred to the new portable telephone with the services that mobile communications companies provide. Naturally, the save data is also not transferred.
In the prior art, several technologies have been introduced for synchronizing data between terminals. For example, ane-mail system has been proposed where a proxy server, which is provided with a terminal information database that registers terminals that are used and an e-mail list database that retains acquisition/deletion information of e-mail for the registered terminals, accesses a mail server to synchronize e-mail between the registered terminals (see Japanese Patent Application Laid-Open Publication (JP-A) No. 2002-244979). An information synchronizing method has also been proposed which, when a terminal in use is switched to non-use, allows work to be continued on a forwarding terminal by transmitting work content to an information synchronizing server, with the information synchronizing server transferring the work content to the other terminal (see JP-A Nos. 2003-242106 and 2004-54633).
With respect to network games also, similarly in the prior art, there are many instances where the save data of the user is saved to a server disposed on the Internet (e.g., a game server for processing network games, etc.). When the user continues playing, using an Internet café PC, the game that the user had been playing on the user's home PC (e.g., when an application program for network games is started), the user can pick up from where the user left off and resume the network game by acquiring the save data saved in the server.
However, in the prior art, even if the user has not changed terminals, the save data is downloaded from the server when the application program for the network game is started. It is necessary to acquire the save data from the server if the user has changed terminals, but if the user has not changed terminals, the save data only needs to be separately saved in that terminal and read.
In this manner, excessive communication has occurred in which the save data is downloaded from the server when the user has not changed terminals. Such excessive communication is not preferable for the user because an excessive monetary burden is placed on users whose communication charges are not at a fixed rate. In comparison to a PC or the like, this problem becomes particularly pronounced when the user plays a network game on a portable terminal such as a portable telephone or PDA, where the fixed-rate system of communication fees has not spread that much.
Also, sometimes the user experiences an inconvenience when the acquisition of the save data from the server is conducted during initialization when the application program is started and the time required for initialization becomes long. In comparison to a PC or the like, this problem also becomes pronounced when the user plays a network game on a portable terminal whose hardware has a low processing capability.
These problems have the potential to reduce the user's desire to play network games and distance the user. Moreover, there is the potential to place an excessive servicing burden for processing excessive communication on people who provide network games as a service.